The present invention relates to improvements in auxiliary devices for increasing the traction and braking capabilities of vehicles under ice and snow conditions.
In the past, only two major types of devices for increasing the traction and braking capabilities of vehicles under ice and snow conditions have proven to be practical. These are tires having special snow-type treads, usually with studs to provide traction on ice, and cross-link devices which attach to the tire and stretch transversely across the tread surface, commonly referred to as "tire chains."
While studded snow tires are helpful on icy surfaces, their effectiveness on surfaces having substantial snow accumulation is limited. Moreover, their studs cause a high degree of damage to roads and highways, and therefore they can remain on the vehicle only during the winter months, requiring vehicle owners to change between stud-type and studless tires twice each year, which is bothersome and costly.
Tire chains are far more effective under snow accumulation conditions than are studded snow tires. However, they cannot be driven on road surfaces having no snow accumulation without quickly wearing and breaking. In most cases, the problem is aggravated by the fact that side roads remain snow covered after main highways have become bare, presenting the ordinary commuter with the dilemma of whether to use his chains or remove them. Unfortunately, the chains are quite difficult to install, normally requiring a person to lie on the ground, and are not much easier to remove, leading most motorists to try first to drive without them and install them only after serious difficulty is encountered. As a result, significant numbers of motorists each winter sustain vehicle damage and physical injury from collisions with other vehicles under snow conditions.
Despite the foregoing obvious deficiencies of snow tires and tire chains, no commercially viable, improved alternative for the ordinary automobile has been developed. Attempts have been made to find viable alternatives as evidenced, for example, by the traction devices shown in U.S. Pat. Nos. 1,361,331, 2,562,758, 2,924,486, 3,184,268 and 3,356,171. Such devices have not succeeded commercially for numerous reasons. Their installation on the vehicle is difficult and costly, largely because they require major alteration to the vehicle due to the requirement that they be placed on the interior side of each vehicle wheel, necessitating major reconstruction of the wheel and axle assembly to render them functional. Additionally, they cannot perform their traction functions while retaining the cushioning function of the pneumatic tire; instead, they substitute a rigid interconnection between the vehicle axle and their traction members, eliminating the resilient interconnection normally provided by the tire. This not only significantly increases the roughness of the ride of the vehicle when such devices are in use (far more so than tire chains which retain much of the cushioning function of the tire), but also causes sever impact loading of the traction members, greatly limiting their resistance to wear and fracture. Moreover, such devices are not readily adaptable to different sizes of wheels, and require the difficult and complicated installation of rotary electrical couplings if they are to be remotely or automatically actuatable.